Magnetic materials are used, for example, in magnetic memory cells and magnetic sensors. A Magnetoresistive Random Access Memory (MRAM) is a non-volatile computer memory technology that uses magnetic charges to store data. A MRAM includes an array of magnetoresistive memory elements or cells. In one example, each memory cell typically has a structure that includes multiple magnetic layers separated by various non-magnetic layers. In general, storing data is accomplished by applying magnetic fields to the magneto resistive memory cells, and thereby causing the magnetic material in the memory cells to be magnetized into either of two possible memory states. Recalling data is accomplished by sensing resistance changes in the memory cell when magnetic fields are applied. The magnetic fields are created by passing currents through word lines external to the magnetic structure or through the magnetic structures themselves.
There is a growing interest in the development and use of MRAM devices for data retention because an MRAM combines the speed of static random access memory with the non-volatility of flash memory. In addition, MRAM has relatively low power consumption, good reliability characteristics, and suffers little degradation over time in comparison to Flash memory. Unfortunately, a problem with MRAM devices is that interference from any external magnetic field can cause errors during programming.
Due to its advantages of speed, non-volatility, relatively low power consumption, reliability, and durability, it is desirable to provide a magnetoresistive memory device and packaging methodology that results in a high performance memory having higher effective density than prior art devices. Moreover, the magnetoresistive memory device must be effectively shielded to prevent problems associated with external magnetic fields.